/Engine/Source/Runtime/Engine/Classes/Engine/Engine.h
If this function returns true, the DynamicSourceLevels collection will be duplicated for the given map. This is necessary to do outside of the editor when we don't have the original editor world, and it's not safe to copy the dynamic levels once they've been fully initialized, so we pre-duplicate them when the original levels are first created.
virtual bool Experimental_ShouldPreDuplicateMap ( const [FName](API\Runtime\Core\UObject\FName) MapName ) const